This invention relates to the recovery of uranium from certain solutions.
Uranium intended for use as fuel in nuclear reactors is almost invariably enriched in the isotope U-235 while in the form of uranium hexafluoride and is shipped in that form to the fuel fabrication plants. At the plant, it is converted to uranium dioxide, UO.sub.2. One of the processes used for this conversion is termed the "ammonium diuranate process (ADU)". According to this process, the UF.sub.6 is first hydrolyzed with water to uranyl fluoride, UO.sub.2 F.sub.2. This is then reacted with ammonium hydroxide to precipitate ammonium diuranate (NH.sub.4).sub.2 U.sub.2 O.sub.7. The last-named compound is calcined to form UO.sub.2 which is the most common reactor fuel.
While the above is a general outline of the process, there are of course, various separation and purification steps involved. A waste solution is produced which contains substantial amounts of uranium. This solution has been, in some instances at least, stored in large ponds or lagoons. The uranium concentration is too high to permit direct discharge into sewers, and, moreover, the uranium, being in the enriched form, has considerable economic value. It is therefore highly desirable to provide a simple, economic process for the recovery of sufficient uranium to reduce the concentration to a value low enough to permit its discharge into the sewers and to obtain the uranium in a form from which it can be recovered and converted into UO.sub.2.